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Module 3c3. The 5th generations CPUs - continued

Pentium MMX (P55C)

The P55C Pentiums were introduced January 8, 1997. MMX
is a new set of instructions (57 new integer instructions, four new data
types, and eight 64 bit registers), which expand the capabilities of the
CPU. It is an addition to the original Pentium set of instructions.

The MMX instructions were designed for multimedia programs. The programmers
can utilize these instructions in their programs. These allow the Pentium
to provide improved program execution.

Both Cyrix and AMD use MMX in their 6th generation CPUs (K6 and M2).
Programs, which are written with MMX instructions, can still be run on,
for example, a Pentium without MMX. However, execution is slower with the
traditional instructions.

More L1 cache and higher clock frequency

Compared to the Pentium Classic, the Pentium MMX were further improved
with 32 KB L1 cache (the old one had 16 KB). There were also other improvements
in the CPU. These improvements together meant 10-20% better performance
at similar clock speeds. The clock frequency of the new processors were
166, 200 and 233 MHz.

Dual voltage

The P55C required a new motherboard. Not because of MMX - that is pure
software, but because of changes in the power supply.
The P55C operated with
dual voltage technology. To reduce heat generation,
this chip requires two different voltages: 2.8 Volt to the nucleus
and 3.3 Volt to the I/O section. The old motherboards for the P54Cs have
only one voltage to the CPU. Thus, the new CPU requires a new motherboard.

Tillamook

For use in laptops Intel has a special power-saving version of the Pentium
MMX. The so-called Tillamook processor is manufactured using 0.25 micron
technology, and you find it in 266 and 300 MHz versions.

IDT Winchip

IDT was another smaller company to produce low-priced Pentium
MMX-like CPUs. Their first WinChip C6 was introduced in May 1997. The company
wanted to deliver 200 MHz Pentium MMXs for $50.

About the IDT WinChip C6 CPU

5.4 million transistor

0.35 micron, 4-layer metal CMOS technology

Socket 7 compatible

200 MHz

About the WinChip 2 3D, released May 19, 1998

Socket 7 processors running at 266 MHz and 300 MHz

0.25-micron process technology

2.5-volt IBM Blue Logic technology

6 million transistors

Die size only 88mm2 making it the smallest x86 processor in
the world

Superscalar MMX and 3DNow!

Fully pipelined floating point unit

100 MHz bus support
IDT expected to continue the development of their WinChips. They wanted to
double up the L1 cache for better performance and to introduce a superpipeline
technology, which also will speed up the whole thing.

We never saw many IDT chips in my country.

In 1999 the company was taken over by VIA who integrates the IDT technology in their Cyrix processor line.

Voltages - dual voltage

One of the most important CPU technologies is the continually
thinner wires inside the chip. With thinner wires, the CPU can operate
at lower voltage. That results in a smaller CPU generating less heat
and with the ability to operate at higher speeds. A step in this development
is the design of dual voltage chips:

The interface to the I/O bus, which always requires 3.3 volt.

In internal CPU parts, it is advantageous to reduce the voltage as much
as possible. This can be done because of the extremely thin wires in the
CPU.
The Socket 7 motherboards have a two part voltage regulator to match
the needs of the CPU. Here are some selected CPUs and their voltage requirements: